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1.
In this work, coupled ZnO/SnO2 photocatalysts were prepared in a rotating packed bed (RPB) via co-precipitation. The precursors of coupled ZnO/SnO2 photocatalysts were formed from solutions of zinc sulfate, tin tetrachloride and sodium hydroxide. The calcinations of these precursors yielded coupled ZnO/SnO2 photocatalysts. The effect of calcination temperature on the characteristics and photocatalytic activity of coupled ZnO/SnO2 photocatalysts was studied. The photocatalytic activity of coupled ZnO/SnO2 photocatalysts was evaluated using the photocatalytic decolorization of methylene blue. The experimental results reveal that coupled ZnO/SnO2 photocatalysts that were obtained by calcination at 600 °C for 10 h were the most efficient in decolorizing methylene blue. 相似文献
2.
《Catalysis communications》2005,6(6):399-403
Liquid phase Claisen–Schmidt condensation between 2′-hydroxyacetophenone and benzaldehyde to form 2′-hydroxychalcone, followed by intramolecular cyclisation to form flavanone was carried out over zinc oxide supported metal oxide catalysts under solvent free condition. The reaction was carried out over ZnO supported MgO, BaO, K2O and Na2O catalysts with 0.2 g of each catalyst at 140 °C for 3 h. Magnesium oxide impregnated zinc oxide was observed to offer higher conversion of 2′-hydroxyacetophenone than other catalysts. Further MgO impregnated with various other supports such as HZSM-5, Al2O3 and SiO2 were also used for the reaction to assess the suitability of the support. The order of activity of the support is ZnO > SiO2 > Al2O3 > HZSM-5. Various weight percentage of MgO was loaded on ZnO to optimize maximum efficiency of the catalyst system. The impregnation of MgO (wt%) in ZnO was optimized for better conversion of 2′-hydroxyacetophenone. The effect of temperature and catalyst loading was studied for the reaction. 相似文献
3.
M. Fassier N. Chouard C.S. Peyratout D.S. Smith H. Riegler D.G. Kurth C. Ducroquetz M.A. Bruneaux 《Journal of the European Ceramic Society》2009,29(4):565-570
The coating of fired clay substrates with various metal oxides, such as anatase, rutile, zinc oxide and tin oxide was achieved using a simple spraying technique followed by a thermal treatment. The photocatalytic activity of the layer was characterized through measurement of the absorption spectrum, in the range 400–800 nm, of methylene blue deposited on top of the coating. Results show that the presence of anatase enhances the degradation of methylene blue when it is exposed to ultraviolet light. Thermal treatment at 1050 °C transforms anatase crystals into thermodynamically stable rutile. This results in a decrease of the photocatalytic activity, which can be explained by increase of the grain size and by a difference in the crystal structure. Measurements of the photocatalytic activity of ZnO and SnO2 show that these two oxides also exhibit photocatalytic properties. In particular, ZnO is a promising alternative material to anatase. 相似文献
4.
Atsunori Matsuda Tomohisa Kambayashi Yusuke Daiko Hiroyuki Muto Mototsugu Sakai 《Journal of the European Ceramic Society》2010,30(5):1151-1158
The surface of H2Ti4O9·xH2O titanate nanosheets was modified using the sulfonated tetrafluoroethylene-based polymer Nafion®, via layer-by-layer assembly. The surface modification allowed the titanate nanosheets to be highly dispersed in hydrophobic organic solvents. Thick films of surface-modified nanosheets were prepared on indium tin oxide (ITO)-coated glass substrates as a negative electrode by electrophoretic deposition. The thickness of the films increased with increasing deposition time and grew to more than 8 μm in 600 s under potentiostatic conditions at 7.5 V. The electrophoretically deposited thick films showed significant hydrophobicity with contact angle for water 95°, and enhanced adsorption and higher photocatalytic activity for hydrophobic dyes such as thionine than those of thick films prepared from unmodified titanate nanosheets. 相似文献
5.
《Ceramics International》2017,43(16):13063-13068
PbTiO3 (PTO), Pb(Mn0.1Ti0.9)O3 (PMTO), Pb(Sr0.1Ti0.9)O3 (PSTO), and Pb(Zr0.1Ti0.9)O3 (PZTO) were prepared on an indium tin oxide (ITO)/glass substrate by a sol-gel method. PTO, PMTO, PSTO, and PZTO films exhibited energy band gaps of 3.55 eV, 3.63 eV, 3.59 eV, and 3.66 eV, respectively. All these films generated high photocurrents due to high shift currents, because carrier migration channels were successfully introduced by a lattice mismatch between the films and ITO substrates. The PMTO thin film exhibited the best ferroelectric and photovoltaic properties, with a photovoltage of 0.74 V, a photocurrent density of 70 μA/cm2, and a fill factor of 43.34%, which confirms that shift current and ferroelectric polarization are two main factors that affect the ferroelectric photovoltaic properties. The PSTO, PZTO, and PTO thin films displayed space-charge-limited current (SCLC) when the electric field strength was below 10 kV/cm, and these three films broke down when the electric field strength was above 10 kV/cm. Analysis of the shift current mechanism confirmed that the breakdown of the PZTO and PSTO thin films resulted from Pool Frenkel emission current. The PMTO thin film displayed SCLC in the test range, which indicates that doping with Mn could inhibit defect formation in ferroelectric thin films. 相似文献
6.
Ag3PO4 nanoparticles with 50–100 nm in size distributed on the surface of ZnO nanorods with ca. 20 nm in diameter and 1–2 μm in length have been synthesized by a facile method. The Ag3PO4–ZnO nanorod composites had much higher photocatalytic activity toward degradation of Rhodamine B (RhB) under visible light irradiation than pure ZnO nanorods, and had better recyclability and stability than pure Ag3PO4 nanoparticles. The Ag3PO4–ZnO nanorod composite with the molar ratio of Ag3PO4:ZnO = 1:40 exhibited the highest photodegradation efficiency of RhB (93%), which was 1.5 times of pure ZnO nanorods. 相似文献
7.
《Ceramics International》2016,42(13):14411-14415
Aluminum oxide (Al2O3)/zinc oxide (ZnO) thin films deposited via atomic layer deposition (ALD) are demonstrated to enhance their thermoelectric properties by manipulating them with a nano-thick Al2O3 interface. The overall superlattice structure is tuned by varying the ZnO ALD sequence and the Al2O3 ALD sequence while maintaining the same composition. An aluminum-doped zinc oxide (AZO) thin film is deposited at 250 °C, and the Al2O3 thickness in the superlattice is gradually increased from 0.13 nm to 1.23 nm. The total film composition is fixed at 2% AZO. We observe that an efficient superlattice structure is made with a specific Al2O3 thickness. The thermal conductivity is significantly decreased from 0.57 W/mK to 0.26 W/mK as the thickness of the Al2O3 layer is increased. Additionally, the absolute Seebeck coefficient is increased from 14 μV/K to 65 μV/K. This may be caused by the interface confinement effect and interface scattering between the ZnO layer and the Al2O3 layer. The figure of merit ZT value is 0.14 for the most efficient structure. 相似文献
8.
《Journal of the European Ceramic Society》2007,27(4):1999-2008
Grain growth studies of zinc oxide ceramics have indicated that inversion boundaries (IBs) are growth faults that control the growth of the zinc oxide (ZnO) grains. To substantiate this observation, we designed experiments to study the nucleation of IBs. Low-temperature experiments showed that in the ZnO–SnO2 system, IBs form before the Zn2SnO4 spinel phase and grains with IBs grow exaggeratedly at the expense of the normal ZnO grains until they completely dominate the microstructure. Experiments using ZnO single crystals embedded into ZnO powder with the addition of SnO2, Sb2O3 and In2O3 showed that depending on the oxidation state of the IB-forming dopant ions, there are two competing mechanisms of IB nucleation: (i) internal diffusion, and (ii) surface nucleation and growth. The first mechanism is typical for III+ dopants and is controlled by Zn-vacancy diffusion, whereas the second mechanism holds for all IB-forming dopants and is controlled by chemisorption of the dopants on Zn-deficient (0 0 0 1) surfaces. In both cases, the driving force for the inversion is the preservation of the local charge balance. 相似文献
9.
Chia-Liang Kuo Cheng-Li Wang Horng-Huey Ko Weng-Sing Hwang Kuo-ming Chang Wang-Long Li Hong-Hsin Huang Yen-Hwei Chang Moo-Chin Wang 《Ceramics International》2010,36(2):693-698
The synthesis of zinc oxide (ZnO) nanocrystalline powders for cosmetic applications by a coprecipitation process has been investigated. When the Zn(OH)2 precipitates are calcined at 373 K for 10 min, the crystalline phases comprise the major phase of Zn(OH)2 and the minor phase of ZnO. XRD pattern shows that only ZnO is present and no other phase is detected when the Zn(OH)2 precipitates calcined at 413 K for 10 min. The nanocrystallite size of ZnO increases slightly from 32.3 to 44.3 nm when the calcination temperature increases from 413 to 873 K. The activation energy of ZnO nanocrystallite growth is 2.02 kJ/mol, which reveals that the nanocrystalline ZnO is easily grown at low temperature. The UV transmission of ZnO nanocrystallites in the wavelength range from 290 to 375 nm is about 35%, indicating that the ZnO nanocrystallites have an excellent UV-absorbing capability. 相似文献
10.
《Ceramics International》2016,42(12):13555-13561
In this article, we report a comparative study of the influence of pressure-assisted (1.72 MPa) versus ambient pressure thermal annealing on both ZnO thin films treated at 330 °C for 32 h. The effects of pressure on the structural, morphological, optical, and gas sensor properties of these thin films were investigated. The results show that partial preferential orientation of the wurtzite-structure ZnO thin films in the [002] or [101] planes is induced based on the thermal annealing conditions used (i.e., pressure assisted or ambient pressure). UV–vis absorption measurements revealed a negligible variation in the optical -band gap values for the both ZnO thin films. Consequently, it is deduced that the ZnO thin films exhibit different distortions of the tetrahedral [ZnO4] clusters, corresponding to different concentrations of deep and shallow level defects in both samples. This difference induced a variation of the interface/bulk-surface, which might be responsible for the enhanced optical and gas sensor properties of the pressure-assisted thermally annealed film. Additionally, pressure-assisted thermal annealing of the ZnO films improved the H2 sensitivity by a factor of two. 相似文献
11.
In situ surface modification of TiO2 and ZnO metal oxide particles has been carried out under hydrothermal conditions within a wide range of temperature and pressure (T = 150–400 °C; P = up to 20 MPa). The influence of the surfactant and selective doping with active metal ions on the crystal size, morphology, and photocatalytic activity of TiO2 and ZnO particles has been carried out. A systematic characterization of the product has been carried out using powder XRD, FTIR, TGA, SEM/TEM, and UV–vis spectroscopy. Similarly the photocatalytic activity in these metal oxides varies with the size, shape and dopant metals. 相似文献
12.
《Carbon》2015
The metal grid and reduced graphene oxide (RGO) are both promising transparent conductive materials for replacing the indium tin oxide (ITO) in flexible optoelectronics. However, the large empty area that exists in the grid together with the relatively high sheet resistance of RGO hinder both the materials for practical applications. In this work, we report for the first time a novel strategy for efficient combination of the metal grid and RGO by using a newly developed room-temperature reduction technique. The obtained RGO/metal grid hybrid films not only overcome the shortcomings of individual components but exhibit enhanced optical and electrical performances (Rs = 18 Ω sq−1 and T = 80%) and excellent flexural endurance. With this hybrid film as the window electrode, a highly flexible electrochromic device with excellent stability and ultra-fast response shorter than 60 ms has been successfully fabricated. Considering its high efficiency, high quality, low cost and large area, the strategy would be particularly useful for economically fabricating various metal grid/RGO films which are quite promising high performance transparent and conductive materials for next generation optoelectronic devices. 相似文献
13.
《Carbon》2013
This paper demonstrates all-carbon photovoltaic devices made of amorphous carbon (a-C) and C60 thin films. C60 film is deposited by the sublimation in vacuum and a-C film is synthesized by exposing N2 radicals to C60 during the deposition. C60 is converted into a-C when the rf power is larger than 150 W and the optical band gap decreases with increasing the power. Photovoltaic properties of device with the structure of Al/C60/a-C/indium tin oxide/glass are presented. It is shown that the present cell has a strong spectral response in the wavelength range shorter than 550 nm and a small response at around 620 nm. 相似文献
14.
《Ceramics International》2016,42(14):15338-15342
2 at% Manganese-doped Na0.5Bi0.5TiO3 (NBTMn) thin films with single-layer thicknesses ranging from 15 to 45 nm/l were deposited on the indium tin oxide/glass substrates by a metal organic decomposition process and spin coating technique. The influence of single-layer thickness on the crystal structure, surface morphology, insulating ability, ferroelectric and dielectric properties was mainly investigated. Compared with the other films, NBTMn film with a single-layer thickness of 30 nm/l exhibits the (110)-preferred orientation and dense structure. Also, it shows the enhanced ferroelectricity with a large remanent polarization (Pr) of 38 μC/cm2 due to the preferred orientation and low leakage current density. Meanwhile, a high dielectric tunability of 39% for NBTMn with 30 nm/l can be observed by varying the measuring applied voltage and frequency. These results indicate that the suitable layer thickness is beneficial to improve the electrical performances of NBTMn thin film. 相似文献
15.
New transparent and high infrared reflection films having the sandwich structure of SiO2/Al:ZnO(AZO)/SiO2 were deposited on the soda-lime silicate glass at room temperature by radio frequency (R.F.) magnetron sputtering. The optical and electrical properties of SiO2 (110 nm)/AZO (860 nm)/SiO2 (110 nm) sandwich films were compared with those of single layer AZO (860 nm) films and double layer SiO2 (110 nm)/AZO (860 nm) films. The results show that these sandwich films exhibit high transmittance of over 85% in the visible light range (380–760 nm), and low reflection rate of below 4.5% in the wavelength range of 350–525 nm, which is not shown in the conventional single layer AZO (860 nm) films and double layer SiO2 (110 nm)/AZO (860 nm) films. Further these sandwich films display a low sheet resistance of 20 Ω/sq by sheet resistance formula and high infrared reflection rate of above 80% in the wavelength range of 15–25 μm. In addition, the infrared reflection property of these sandwich films is determined mainly by the AZO film. The outer SiO2 film can diminish the interference coloring and increase transparency; the inner SiO2 film improves the adhesion of the coating to the glass substrate and prevents Ca2+ and Na+ in the glass substrate from entering the AZO film. 相似文献
16.
《Ceramics International》2017,43(2):2033-2038
Fe-doped Na0.5Bi0.5TiO3 (NBTFe) thin films were prepared directly on indium tin oxide/glass substrates using a chemical solution deposition method combined with sequential layer annealing. The X-ray diffraction, scanning electron microscopy and insulating/ferroelectric/dielectric measurements were utilized to characterize the NBTFe thin films. All the NBTFe thin films prepared by four precursor solutions with various concentrations of 0.05, 0.10, 0.20 and 0.30 M exhibit polycrystalline perovskite structures with different relative intensities of (l00) peaks. A large remanent polarization (Pr) of 33.90 μC/cm2 can be obtained in NBTFe film derived with 0.10 M spin-on solution due to its lower leakage current and larger grain size compared to those of other samples. Also, it shows a relatively symmetric coercive field and large dielectric tunability of 36.34%. Meanwhile, the NBTFe thin film with 0.20 M has a high energy-storage density of 30.15 J/cm3 and efficiency of 61.05%. These results indicate that the electrical performance can be controlled by optimizing the solution molarity. 相似文献
17.
《Ceramics International》2017,43(11):8289-8293
In this work, zinc oxide (ZnO) nanostructures were successfully synthesized by thermal oxidation of zinc (Zn) coated steel substrates. Zn coatings were electrodeposited on the mild carbon steel sheet in the sulfate bath by DC current. The zinc coated samples were oxidized in air at distinct annealing temperatures between 400 °C and 800 °C. The phase structure and surface morphology of the ZnO films were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of these ZnO layers was examined by means of decomposition of methylene blue (MB) aqueous solutions under UV lamp irradiation for various duration. The findings illustrated that annealing temperatures had a big effect on the morphology and structure of the ZnO layers. The annealed layers showed significantly enhanced photoactivity activity than the pure Zn layer under UV-irradiation. The sample with ZnO nanostructures oxidized at 800 °C exhibited a better photocatalytic degradation of MB than the other samples. This paper can provide an important contribution to the development of efficient photocatalysts for the solution of the environmental pollution problems. 相似文献
18.
《Ceramics International》2017,43(9):6765-6770
Herein, we report the simple synthesis, characterization and acetone gas sensing applications of Ag-doped ZnO nanoneedles prepared by facile hydrothermal method. The synthesized nanoneedles were characterized through different characterization techniques to examine its crystallinity, phase structure, morphological, compositional, optical, vibrational and gas sensing properties. The detailed morphological studies revealed that the Ag-doped ZnO nanoneedles are assembled into non-homogeneously distributed flower-shaped structures which are grown in high density. Further characterizations confirmed that the synthesized nanoneedles are pure, possessing well-crystallinity and exhibiting good optical and vibrational properties. The synthesized Ag-doped ZnO nanoneedles were used as functional material to fabricate high sensitive acetone gas sensors. The effect of operating temperature and concentration of the acetone were analyzed for detailed sensing performance of synthesized nanoneedles. By detailed sensing experiments, the response and recovery times of 10 s and 21 s, respectively were calculated at acetone concentration of 100 ppm at an optimized operating temperature of 370 °C. A maximum sensitivity of 30.233 was recorded at 370 °C operating temperature for 200 ppm of acetone for the fabricated acetone sensor based on Ag-doped ZnO nanoneedles. 相似文献
19.
《Ceramics International》2017,43(5):4127-4130
In the present study, the effect of indium doping on the micro-characteristics and electrical properties of ZnO varistors co-doped with Al2O3 and Y2O3 were determined. Scanning electron microscopy, current-voltage testing in a range from small to large current, capacitance-voltage testing, and X-ray diffraction pattern testing were conducted. The results show that both the residual voltage ratio and the leakage current of sintered ZnO varistors decrease and then increase as the indium dopant increases at a given aluminum and yttrium content. The nonlinear coefficient shows an inverse relationship. In addition, the voltage gradient of the samples increases as the indium dopant increases. The sintered ZnO varistor samples with 0.02 mol% indium, 0.2 mol% aluminum, and 0.9 mol% yttrium show the optimal performance, exhibiting a 1-mA residual voltage of 448 V/mm, a leakage current of 0.69 µA/cm2, a nonlinear coefficient of 76, and a residual voltage ratio of 1.58. This study has great significance for improving the protective effects of surge protection devices assembled with ZnO varistors and the stability of power systems. 相似文献
20.
Naoki Matsunaga Yoshihiro Hirata Yousuke Fukuda Soichiro Sameshima 《Ceramics International》2009,35(2):693-698
Direct current in the range from 50 to 390 mA/cm2 was flowed between alumina/tin-doped indium oxide (indium tin oxide, ITO) composite (cathode) and carbon (anode) electrodes in an aqueous solution containing TiCl4 and (NH4)2SO4 at pH 0.5. The composite electrode dissolved in the solution and was precipitated again on the surface of the electrode. The thickness of precipitated layer increased at a higher applied charge. During the electrolysis, TiO2 was also deposited on the surface of precipitated layer. The amorphous TiO2 heated at 300 °C and sintered Al2O3–ITO composite showed a good adsorption property of electromagnetic energy in the wide wavelength of 200–800 nm. 相似文献